This invention relates generally to radio frequency data communication signal receivers, and more particularly to radio frequency processing and discrimination principles.
Analog implementations of signal processing have long been used in radio receivers. Although analog integrated circuits are often referred to as linear, such circuits are completely dependent on a variety of manufacturing technologies which generate a product, often producing outputs which are only analogous or similar to the input signals.
Digital signal processors (DSPs) began to impact the industrial and communication areas in the 1970's and 1980's due to their improved sensitivity and the characteristic of generally widespread compatibility of digital devices. DSPs are noted for their linearity in conversion of information signals, general imperviousness to age and temperature, and relative independence of sampling rates with concomitant reduction of chip area requirements and associated time demands pursuant thereto. DSPs, however, often contain sophisticated programmable circuitry that necessitates significant microprocessor or microcomputer memory; this aspect often is costly. In addition, the programmable aspect of DSPs is very power-consuming.
Although digital signal processing technology has been combined with analog implementation to achieve a result for discriminators which far improves the analog system alone, it is desirable to have the advantages of digital discrimination without the associated present costs.